Water-soluble films and their use in forming water-soluble articles are well known in the art.
U.S. Pat. No. 3,186,869, issued Jan. 29, 1962, COATED FILM FOR LAUNDRY PACKAGE, and U.S. Pat. No. 3,322,674, issued Jun. 26, 1964, LAUNDRY PACKAGE, disclose water-soluble films and laundry articles made therefrom which contain a detergent and chorine based bleaching agent. The water-soluble films in these references are internally coated with a wax or other material to prevent the contents of the package from interacting with the film material and degrading its solubility characteristics.
U.S. Pat. No. 3,413,229, issued Nov. 26, 1968, POLYVINYL ALCOHOL COMPOSITIONS, teaches the use of a plasticizer in PVA compositions that are used to form laundry packets for detergents and/or bleaches in order to maintain the solubility characteristics of the film after storage.
U.S. Pat. No. 3,892,905, issued Jul. 1, 1975, COLD WATER SOLUBLE PLASTIC FILM, discloses a cold water soluble film that comprises a combination of polymers having different molecular weights. The lowest molecular weight polymer suggested is about 21,000.
U.S. Pat. No. 4,119,604, issued Oct. 10, 1978, POLYVINYL ALCOHOL COMPOSITIONS FOR USE IN THE PREPARATION OF WATER-SOLUBLE FILMS, discloses a cold water soluble film that comprises a low molecular weight PVA and a medium molecular weight PVA. The “low” and “medium” molecular weights are not identified but are merely described in terms of the viscosity of a solution containing the polymer.
U.S. Pat. No. 4,481,326, issued Nov. 6, 1984, WATER-SOLUBLE FILMS OF POLYVINYL ALCOHOL AND POLYVINYL PYRROLIDONE, discloses a cold water soluble film for packaging various products. The film comprises hydrolyzed polyvinylacetate alcohol and polyvinyl pyrrolidone. Specific data concerning the dissolution rate of the film in cold water is not disclosed.
U.S. Pat. No. 4,544,693, issued Oct. 1, 1985, WATER-SOLUBLE FILM, discloses a water-soluble film that reportedly dissolves in water as cold as 5° C. The film is composed of polyvinyl alcohol, polyvinyl pyrrolidone, ethoxylated alkyphenol, and polyhydric alcohol. No dissolution data concerning the claimed film is provided.
U.S. Pat. No. 4,692,494, issued Sep. 8, 1987, WATER-SOLUBLE FILMS OF POLYVINYL ALCOHOL AND POLYACRYLIC ACID AND PACKAGES COMPRISING SAME, discloses a cold water soluble film made of a blend of PVA and polyacrylic acid.
U.S. Pat. No. 4,765,916, issued Aug. 23, 1988, POLYMER FILM COMPOSITION FOR RINSE RELEASE OF WASH ADDITIVES, discloses water-soluble laminate film that comprises at least one methylcellulose layer of hydroxybutyl methylcellulose (HBMC) blended with hydroxypropyl methylcellulose (HPMC) and at least one layer of polyvinyl alcohol incorporating a cross-linking agent. The solubility of the laminate is intended to be pH rather than temperature dependent.
U.S. Pat. No. 4,801,636, issued Jan. 31, 1989, RINSE SOLUBLE POLYMER FILM COMPOSITION FOR WASH ADDITIVES discloses a water-soluble film that is made from a blend of polyvinyl alcohol and alkyl cellulose and has a metalloid oxide component to inhibit the dissolution of the film in an alkaline wash but allow dissolution in the less alkaline rinse. U.S. Pat. No. 4,972,017, issued Nov. 20, 1990, is a divisional of U.S. Pat. No. 4,801,636 that is directed to an article made from the film claimed in the '636 patent.
U.S. Pat. No. 5,272,191, issued Dec. 21, 1993, COLD WATER SOLUBLE FILMS AND FILM-FORMING COMPOSITIONS discloses water-soluble film made from known water-soluble film-forming polymers, and a second component that is a water insoluble cellulose material. The cellulose is rendered insoluble preferably through internal or external cross linking reactions.